This invention concerns a timepiece comprising a display arranged to display time data and orientation means sensitive to the direction and sense of the terrestrial magnetic field.
Such arrangements are already known. Referring for example to the French patent application No. 2 438 861 and in particular to FIG. 1 of such application, there may be seen a wrist-watch comprising a dial, of which one portion is employed for digital display of the time by means of a known electronic arrangement and another portion is occupied by a compass which employs a magnetized needle in order to indicate the direction of the magnetic north. As a variant, the cited application proposes the juxtaposition of the compass and a classic analog display comprising hands driven by a stepping motor.
The timekeeping elements and compass with a magnetized needle are also shown in Swiss Pat. No. 346 826, but superposed one over the other, the compass including in addition means for regulating the declination, thereby enabling allowance for the angle which exists between the true north and the magnetic north, and finally, a rotating bezel permitting one to follow a known direction relative to the north.
Such arrangements present the disadvantage of being cumbersome and fragile. Effectively, should one wish to assure a certain precision in aiming the device during a direction finding exercise for instance, it would be necessary to have available a compass needle with a certain length, this condition not being normally fulfilled by the first arrangement proposed hereinabove in which the compass element as miniaturized may indicate only very approximately the direction to be followed. If the second arrangement as cited undoubtedly permits a better precision concerning the direction to be followed, it will be immediately noticed that it is fairly cumbersome since it employs the entire surface of the watch. Moreover, the construction and design of such arrangements requires particular care should one wish to obtain reproducible indications. Thus, there will be required for instance precision pivots which consequently will be shock sensitive and fragile. On the other hand, a compass with a magnetic needle which may be of real use requires a damping of its needle either by a brake using Foucault currents or by means of a liquid which, it will be readily understood, brings about certain complications in the construction and increases the encumbrance. Finally, a mechanical orientation device is poorly adapted to an otherwise completely electronic watch since it reintroduces moving mechanical elements to a product where these have been otherwise eliminated.
The purpose of the present invention is to overcome the hereinabove disadvantages by employing means as fully set forth in the claims.